Natural selection works on the phenotype, rather than genotype, what best explains the reason for this

Genes aren't eradicated from natural selection, but the chances of getting the phenotypes (the physical attributes of an organism based on the genes) go down as the organisms with those phenotypes die out.

Explanation:

Recessive genes are still present in, for example, a heterozygous genotype. but since there is a dominant, it covers the recessive gene and the phenotype won't have anything to do with the recessive gene (unless we are talking about incomplete or codominance).